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J. G. HQDGSON. PROCESS OF CANNING.

APPLICATION FILED ocT.21, 191a.

Patented June 17, 1919.

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To all whom it may concern:

Be it known that 1, JOHN G. Honoson, a citizen of the-United States,residing in Maywood, in the county of Cook and State of Illinois, haveinvented a new and useful Improvement in Processes of Canning, of whichthe following is a specification.

This invention relates to improvement in process of canning and moreparticularly to contents while the can is thus partially exhausted orthe air therein in an attenuated condition. Hitherto, so far as I amaware, friction top cans have never been used, in the carrying out ofthis process on account of the fact that it has generally beenconsidered impossible to obtain an absolutely hermetic or erfectly airtight joint wit the use of friction seals, the use of friction top canshaving been limited generally to transporting paints, pgwders and thellke, which do not have to processed or cooked and which are notpermanentlyinjured by contact with air. Solder cans employing a cap holeor stud hole, which were the first type of cans used in canning orprocessing food products, have gradually been supplanted by what aretermed the sanitary or open top can in which the final closure or coveris double seamed to the can body.

Several difliculties have been encountered in processing food roducts inthe sanitary cans, among whic may be mentioned: exposure of the contentsduring the heating step when the cover is 01f the can which causesscorching of the food products; danger of spilling while the cans arebeing passed through the exhaust box used for heating the contents; anddanger of some of the contents getting on or between the seam formingflanges and thus preventing a perfect joint between the cover and canbody when the latter are seamed. I am aware, however, that recently someof these dithculties encountered with the use of sanitary s ecimen ofmam Patent. P tt -a al ai m, amp, Application filed October a7, 1913'.semi No. rower.-

cans have been overcome by'clenching, sna ping or otherwise securing thecover to t e can body in such a way as to permit the escape of theexpanded gases before the can is passed through the exhaust box or steamcooker, after which the cover and can body are tightly double seamed toseal the can.

I With a double seamed can, however, it is not always possible todetermine whether or not the joint formed is a'perfect one and even whenthe double seam joints are thought to be perfect, actual tests have.proven that if the cans are kept for several years before beincr used,as often happens in the case of exploring parties and places far removedfrom ordinary transportation, air will gradually enter the can throughthe double seams and thus cause deterioration of the food. From thepreceding it will be seen that the container which will keep foodproducts indefinitely must be sealed either by all metal joints orsolder seams such as with the old type of'solder can or with hermeticasket seals. Solder cans, as before pointed out, are gradually beingdiscontinued owing to several disadvantages incident to their use. Ifcans or containers employing a hermetic gasket seal are used, it isnecessary that the process'be so arranged that the cans after belngfilled may be processed by passing through the exhaust box withoutdanger of spilling the contents or of scorchin orburnin the contents andthe final sea lug accomplished at such a'time and in such a manner thatthe partial vacuum within the can will itself practically cause theformation of the hermetic gasket seam.

The object of my invention is to devise a process of cannin whereinfriction top cans employing a gas et hermetic seam may be advantageouslyemployed, 'at the same time insurin a perfect,-absolutely air-tightjoint.

The invention furthermore consists in the novel steps and combinationsof novel steps as herein shown, described or claimed.

In the drawing forming a part of this specification, Figure 1illustrates suitable mechanism for carrying out my improved process andFigs. 2, 3 and 4: are sectional views of a container adapted forcarrying out my process and showing respectively the can as it is firstfilled, the can with the cap loosely applied thereto as it enters theexhaust box and while the contents of the can are being heated and thecan asit is finally closed by means of a frictioncover pressed downagainst the ca to form the hermetic gasket seal between t 1e cap and cantop.

In said drawing the body of the can or other container which may be ofmetal or other suitable material, is designated by the reference 10, thesame having ,a bottom 11 and a top 12 secured thereto. The to '12 isprovided with a countersunk centra portion having an opening 13 thereinsurrounded by a horizontally'disposed shelf or ledge 14 on which isplaced a gasket of rubber or other suitable material 15. The verticalWall 16 of the countersunk portion ofthe cover forms a friction seat cooerable with the friction seat wall 17 o a: countersunk cover 18. v

In carrying out my process, the cans will first be filled, as shown inFig. 2, afterwhich an annularcap 19,will be placed loosely within thecountersunk portion of the can top on'top of they gasket 15. The cap 19is provided with an inturned edge'Q O spaced from the main, slightlydownwardly concaved portion 21" thereof. After the cap is placed inposition, as shown in'Fig. 3, the

air within the can is attenuated and the contents heated by passin thecan through an exhaust box 22 heate by a coil of steam pipe 23, the cansbeingconveye d through the exhaust box asby'means of an endless conveyer24 of any welliknown construction, the exhaust box being provided withflap. doors 25 at each end 'tol better retain the heat therein. Aswillbeapparent, during the passage of the filled cans' through the exhaustbox, the heated and expanded-gases escape freely through the loose ointbetween the cap 19 and the gasket 15 and yet at the same time, thecontents are fully protected from injury andthere is practically nodanger of spilling or escape ofthe cans contents. While the air withinthe can is in the attenuated condition thus created by the heat, afriction cover is placed in proper position and is then forced home by aplunger 26 beneath which the cans may be conveyed after leaving theexhaust box. Inactual practice, the partial vacuum created within thecan after the can coolswill be sutii'cient in itself to draw the capfirmly down against will be-obvious to those skilled in the art that theattenuated condition of the air within the can before the friction coveris applied, may be obtained by placing the filled can within a vacuumchamber and the applying the friction cover-before the can i subjectedto normal or atmospheric pressure; It is also apparent that the hermeticseal formed between the cap, gasket and can top will in itself generallybe all that is neces sary 'to hermetically seal the can, and thatinstead of employing a true friction cover, which of course providesa'friction seal as above indicated, any sort of a frictiona'lly heldcap-retaining member may be used, the function of the'cap retainingmember being to prevent accidentalv removal or dislodg-'80 ment of thecap after the hermetic seal has I been formed. Such a' cap retainingmem- .ber might, for instance, be in the form of an annular membersimilar to the friction top with its central portion cut-out.

In opening the can, the friction cover or friction cap-retaining memberwillfirst be removed in the usual manner, after which the cap willbepunctured by some sharp instrulnent in order to equalize the pressureon both sides of the cap, whereupon the latter may be easily pulled off.

I claim 1 1. The herein described process of cooking and sealing thecontents of cansfn 'hi'ch consists in filling the can with the contentsto be processed or cooked, heating and cookin the contents, sealing thecan by a gasket and superposed closure, and maintaining a me tallicspring pressure on said gasket irrespectiveof any shrinking orsetting-of the same.

2. The process of canning which consists in: filling a can having anopen top; applying a gasket and superposed metallic spring closing caploosely to the top of the can to cover the opening of the ca-n so as toadmit of the escape of air; processing the filled can by heat andattenuating the air within the r can; admitting atmospheric pressure tothe exterior of the can and causing such pressure as the can cools tohold the said loose cap tightly in place so as to close the can againstthe entrance of'air; and, while there is thus maintained more or less ofa vacuum 116 within the can, applying pressure upon the said loosespring cap, and maintaining the spring pressure of the latter onthegasket.

In witness whereof, I have hereunto set my hand this 22nd day ofOctober, 1913, in 1 the presence of two subscribing Witnesses.

JOHN G. HODGSON.

Witnesses: H. M. MUNDY, Josnrir HARRIS.

